In an article by DigitalSpy they review the PS3 console preparing for Launch in the UK. The compare the consoles, power, backwards compatibilty and price point. Here are some quotes from the article:
The driving force behind the PlayStation 3 is its much publicised Cell processor. Co-developed by IBM, Toshiba and Sony, this 3.2Ghz superchip has 64-bit PowerPC processing along with eight separate elements that can be assigned to specific tasks in a game such as handling animation, while another processes the Artificial Intelligence involved.
This increases the speed games run at, but not significantly so as Xbox 360 also has a 3.2Ghz chip built-in.
PlayStation 3 also includes a powerful 550hz Nvidia graphics card, offering true 1080p HD resolution and graphics that are ahead of anything else out there. Play Virtua Tennis 3 or Ridge Racer 7 and you can't fail to be impressed.
Xbox 360 features a 500Mhz graphics card that is undoubtedly stunning, but just falls short of the PS3's visual crispness, speed and immense attention-to-detail."